Oxidative Steam Reforming Of Methanol Research Articles

Hydrogen-Rich Gas Production by Steam Reforming and Oxidative Steam Reforming of Methanol over La0.6Sr0.4CoO3-δ: Effects of Preparation, Operation Conditions, and Redox Cycles.

La0.6Sr0.4CoO3-δ (LSC) perovskite, as a potential catalyst precursor for hydrogen (H2)-rich production by steam reforming of methanol (SRM) and oxidative steam reforming of methanol (OSRM), was investigated. For this purpose, LSC was synthesized by the citrate sol-gel method and characterized by complementary analytical techniques. The catalytic activity was studied for the as-prepared and prereduced LSC and compared with the undoped LaCoO3-δ (LCO) at several feed gas compositions. Furthermore, the degradation and regeneration of LSC under repeated redox cycles were studied. The results evidenced that the increase in the water/methanol ratio under SRM, and the O2 addition under OSRM, increased the CO2 formation and decreased both the H2 selectivity and catalyst deactivation caused by carbon deposition. Methanol conversion of the prereduced LSC was significantly enhanced at a lower temperature than that of as-prepared LSC and undoped LCO. This was attributed to the performance of metallic cobalt nanoparticles highly dispersed under reducing atmospheres. The reoxidation program in repetitive redox cycles played a crucial role in the regeneration of catalysts, which could be regenerated to the initial perovskite structure under a specific thermal treatment, minimizing the degradation of the catalytic activity and surface.

Promoted oxygen release from copper-ceria interfacial sites for selective hydrogen production

The modulation of oxygen species is an effective strategy for selective H2 production with relevant chemical looping processes. This paper describes the promoted oxygen release from CuO-CeO2 redox catalysts for selective H2 production in chemical looping oxidative steam reforming of methanol (CL-OSRM). Despite the complete oxidation of methanol from CuO, the excess H2 production of CL-OSRM with respect to methanol steam reforming (MSR) increases linearly with the amount of active oxygen in CeO2 induced by the copper-ceria interaction. In situ spectroscopic characterizations and mechanistic study demonstrate that copper-ceria interfacial sites induce oxygen release from CeO2 to facilitate the partial oxidation of methoxy to formate species, which promotes the H2 production rate. This study provides an instructive strategy for the construction of redox catalysts for selective H2 production with chemical looping processes.

Gold nanoparticles-assisted sodium borohydride supported on titania as a catalyst for the oxidative steam reforming of methanol and CO oxidation

Gold nanoparticles-assisted sodium borohydride supported on titania as a catalyst for the oxidative steam reforming of methanol and CO oxidation

Influence of nitric acid-assisted hydrothermal conditions on the characteristics of TiO2 catalysts and their activity in the oxidative steam reforming of methanol

Titania (TiO2) nanoparticles (NPs) with different morphologies (spherical, rod-shaped, and mixed) were prepared by hydrothermal treatment of different nitric acid (HNO3)/titanium (IV) isopropoxide (TTIP) molar ratios (0.25, 0.5, 1.0, and 1.7) at different hydrothermal temperatures (90, 150, 200, and 250 °C), hydrothermal times (6, 12, and 24 h), and calcination temperatures (500, 625, and 750 °C). The crystalline structure, morphology, and surface texture of the obtained TiO2 NPs were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherm, field emission-scanning electron microscopy, and high resolution-transmission electron microscopy analyses. Under a larger HNO3: TTIP molar ratio, higher hydrothermal temperature, and higher hydrothermal time, the spherical mixed anatase–rutile phase TiO2 NPs were converted to a nanorod (NR)-shaped rutile phase (TiO2-R). The TiO2-R NRs gave the highest methanol conversion level (65%) and hydrogen yield (45%) in the oxidative steam reforming of methanol at 400 °C.

Ceria nanorod supported gold nanoparticles as structured catalysts for the oxidative steam reforming of methanol: Effect of CTAB concentration on physiochemical properties and catalyst performance

Ceria (CeO2) supports were synthesized by hydrothermal treatment with different Cetyltrimethylammonium bromide (CTAB) concentrations (CeO2-X: 0.135, 0.270, 0.540 and 1.080, where X is the CTAB concentration in mmol). The micro-structures of bundle-like ceria nanorods (NR) were produced by thermal treatment of the crystalline Ce(OH)CO3 precursor. The exposed crystal planes of (200) and (111), corresponding to the d-spacing of 0.27 and 0.31 nm, were confirmed by high resolution-transmission electron microscopy (HR-TEM). The fundamental characteristics of CeO2-0.135 led to the highest surface area, surface area normalized reducibility and oxidized gold species (Aun+/Au0) on the surface, relatively higher oxygen vacancies and a smaller average gold particle size (7.9 nm). The activity results show that the Au/CeO2-0.135 has the highest methanol conversion and H2 production rate for oxidative steam reforming of methanol (OSRM). The reducibility and gold particle size played a crucial role in determining the H2/CO2 ratio at the temperature of 200 °C.

Reforming of methanol to produce hydrogen over the Au/ZnO catalyst

Gold particle with an average size of dAu ~ 4 nm was dispersed on ZnO by the deposition precipitation method. The fabricated Au/ZnO catalyst was used to produce hydrogen from reforming of methanol. Four reforming reactions, i.e., decomposition of methanol (DM), steam reforming of methanol (SRM), partial oxidation of methanol (POM) and oxidative steam reforming of methanol (OSRM), were evaluated in a fixed bed reactor. A reaction temperature of TR > 623 K was required for catalyzing reactions of DM and SRM. Interestingly, high methanol conversion (CMeOH > 90%) was found from reforming reactions of POM and OSRM at an amazing low temperature of TR < 473 K. Besides, a presentable hydrogen yield (RH2 ~ 2.4) and a low selectivity of CO (SCO ~ 1%) were simultaneously attained from the reaction of OSRM. Therefore, the low temperature OSRM reaction over the Au/ZnO catalyst is suggested as a friendly reforming process for on-board production of hydrogen.

Sorption-enhanced chemical looping oxidative steam reforming of methanol for on-board hydrogen supply

Hydrogen is an indispensable energy carrier for the sustainable development of human society. Nevertheless, its storage, transportation, and in situ generation still face significant challenges. Methanol can be used as an intermediate carrier for hydrogen supplies, providing hydrogen energy through instant methanol conversion. In this study, a sorption-enhanced, chemical-looping, oxidative steam methanol-reforming (SECL-OSRM) process is proposed using CuO–MgO for the on-board hydrogen supply, which could be a promising method for safe and efficient hydrogen production. Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process. The effects of CuO/CH3OH, MgO/CH3OH, and H2O/CH3OH mole ratios and of temperature on H2 production rate, H utilization efficiency, CH3OH conversion, CO concentration, and system heat balance are discussed thoroughly. The results indicate that the system can be operated in auto-thermal conditions with high-purity hydrogen (99.50 vol%) and ultra-low-concentration CO (< 50 ppm) generation, which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells (LT-PEFMCs) with the SECL-OSRM process. The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H2O/CH3OH and MgO/CH3OH mole ratios.

Chemical looping induced CH3OH–H2-PEMFC scheme for fuel cell vehicle: Parameter optimization and feasibility analysis

In this work, a hybrid system combined with chemical looping methanol reformer (CL-reformer) and high-temperature proton exchange membrane fuel cell (HT-PEMFC) is proposed for the vehicle power supply. The Cu-based chemical looping induced methanol reforming is introduced to optimize the energy supply scheme of fuel cell vehicles. The start-up and working stages of the integrated system are comprehensively considered and simulated via the ASPEN Plus software. In start-up stage, the lattice oxygen participates the oxidative steam reforming of methanol, achieving auto-thermal hydrogen generation and Cu-based oxygen carrier (OC) reduction (Cu2+→Cu0), and the reduced OC can be regenerated by the air oxidation (Cu0→Cu2+); In working stage, the reduced OC (Cu0) plays the role of catalyzing methanol conversion, and the heat generated from HT-PEMFC stack can be recovered by the methanol reforming module. The effects of CL-reformer conditions on the methanol reformate quality and the performance of HT-PEMFC stack are investigated. Furthermore, the feasibility of maintaining thermally neutral of the integrated system is discussed. Simulation results indicate that the CL-reformer-HT-PEMFC system can achieve auto-thermal operation, in which the system electrical efficiencies of 21.6%–26.7% and 47.7% can be obtained at start-up and working stages, respectively.

Hydrogen generation from methanol reforming for fuel cell applications: A review

Methanol is regarded as an important liquid fuel for hydrogen storage, transportation, and in-situ generation due to its convenient conveyance, high energy density, and low conversion temperature. In this work, an overview of state-of-the-art investigations on methanol reforming is critically summarized, including the detailed introduction of methanol conversion pathways from the perspective of fuel cell applications, various advanced materials design for catalytic methanol conversion, as well as the development of steam methanol reformers. For the section of utilization pathways, reactions such as steam reforming of methanol, partial oxidation of methanol, oxidative steam reforming of methanol, and sorption-enhanced steam methanol reforming were elaborated; For the catalyst section, the strategies to enhance the catalytic activity and other comprehensive performances were summarized; For the reactor section, the newly designed steam methanol reformers were thoroughly described. This review will benefit researchers from both fundamental research and fuel cell applications in the field of catalyzing methanol to hydrogen.

Hydrogen Production on Cu-Ni Catalysts via the Oxy-Steam Reforming of Methanol

In this work, bimetallic Cu-Ni catalysts supported on binary oxides containing ZnO, ZrO2, CeO2 and Al2O3 were investigated in hydrogen production via the oxidative steam reforming of methanol (OSRM). Their physicochemical properties were extensively studied using various methods such as BET, TPR-H2, TPD-NH3, XRD, SEM-EDS, ToF-SIMS and XPS. The reactivity measurements showed that the active phase and support composition played an important role in the activity of the catalyst in the OSRM. The most active system at higher temperatures was 30% Cu–10% Ni/CeO2·Al2O3, with high catalytic activity attributed to the Cu0.8Ni0.2 alloy formation. In addition, the reactivity results showed that the most active catalyst exhibited high acidity and was easily reduced. At low temperatures, the best catalytic properties were exhibited by 30% Cu–10% Ni/ZrO2·Al2O3. The reactivity and physicochemical properties of the studied catalysts confirmed the crucial role of alloy composition on their catalytic properties in the oxy-steam reforming of methanol. The obtained results validate the possibility of using Cu-Ni catalysts for hydrogen production.

Chemical looping oxidative steam reforming of methanol: A new pathway for auto-thermal conversion

Auto-thermal reforming of methanol is an attractive route for low-temperature methanol conversion for hydrogen production. This paper describes utilization the lattice oxygen of Cu2O/Ca2Fe2O5 participates the partial oxidation of methanol to achieve the efficient auto-thermal reforming of methanol. ASPEN Plus software was adopted to verify the feasibility of auto-thermal conversion of methanol via Cu↔Cu2O looping and provided a comprehensive understanding of the associated process via operating parameter optimization. A series of CuO/Ca2Fe2O5 with different contents of copper were prepared as the catalytic oxygen carrier (COC) which goes through the reduction → catalytic methanol conversion →re-oxidation. The surface and bulk properties of COCs were characterized by XRD, XPS, TEM-EDS mapping, Raman, and H2-TPR; the reaction pathways were investigated using CH3OH-pulse and in situ DRIFTS. Results indicate that 40 % Cu-loaded Cu2O-Ca2Fe2O5 shows the highest catalytic activity of the synthesized COCs, and the presence of Ca2Fe2O5 tunes the redox activity and mobility of the lattice oxygen, obtaining a H2 production rate of 37.6 μmol·H2∙g−1·COC·s−1 at 240 °C. The reaction pathways of chemical looping methanol conversion follow the sequence: CH3OH full oxidation → formaldehyde intermediate → methyl-formate intermediate as the amount of lattice oxygen decreases gradually.

A hybrid phosphorus-acid fuel cell system incorporated with oxidative steam reforming of methanol (OSRM) reformer

In this paper, a phosphoric acid fuel cell integrated with reformer and evaporator is demonstrated. Oxidative steam reforming of methanol (OSRM) process is employed in this system in cooperated with a high efficient evaporator, and the reacted gas is sent into a phosphorus-acid fuel cell (PAFC) for direct power generation after surplus methanol/water filtration. The results show that the maximum power density of this hybrid system achieves 277 mW/cm2 without CO2 removal, while it achieves 485 mW/cm2 when employing pure hydrogen as the fuel.

The influence of the size of metal particles on the catalytic activity of Ni and Cu-supported catalysts in methanol reforming reaction

The aim of the work was to investigate how the size of Ni and Cu-supported nanoparticles influence their activity in an oxidative steam reforming of methanol. The size of metal particles was controlled by the initial introduction or elimination of oxygen-containing groups on the surface of carbon nanotubes. The results of the activity tests showed that catalysts with the smallest metal nanoparticles were the least active since they easily underwent oxidation during the process.

Effect of acid on the crystalline phase of TiO2 prepared by hydrothermal treatment and its application in the oxidative steam reforming of methanol

Titania (TiO2) supports with anatase (A), mixed, and rutile (R) crystalline phases were prepared via the hydrothermal treatment of titanium isopropoxide and investigated as a catalyst for the oxidative steam reforming of methanol (OSRM). The different TiO2 phases were synthesized using different types of acid: acetic (HAc), nitric, and a mixture of HAc and hydrochloric acids, and hydrothermal (90 or 200 °C) or calcination (560 or 750 °C) temperatures. X-ray diffraction analysis revealed the crystal structure of successfully synthesized TiO2 with different TiO2-A:TiO2-R ratios. The TiO2-R with (110) and (101) planes showed the highest catalytic activity for OSRM in the temperature range of 200–400 °C.

Dependence of the CeO2 morphology in CuO/CeO2 catalysts for the oxidative steam reforming of methanol

Copper oxide on ceria supports (CuO/CeO2) were investigated as catalysts for the oxidative steam reforming of methanol (OSRM) reaction at 200–400 °C. Different shapes of CeO2 were obtained, as rod-, mixed- (rod and cube) and cube-shaped with an exposed surface of (110) + (100), (110) + (100) and (100) planes by variation in the hydrothermal synthesis temperature (100–220 °C). The CuO was deposited on CeO2 by deposition–precipitation at a nominal 10% by weight and the obtained CuO/CeO2 catalysts were characterized. The morphological structure of CeO2 influenced the catalytic activities in the OSRM reaction. The CuO/rod-shaped CeO2 (CuO/CeO2-R) gave the highest turnover frequency (TOF) and a CO concentration of less than 1% (v/v). The high catalytic performance of CuO/CeO2-R involved the well-dispersed CuO nanoparticles, level of Cu+ species as the active site, improved reducible oxide, number of relative oxygen vacancies and the stronger interaction between CuO and CeO2.

Effect of synthesis time on morphology of CeO2 nanoparticles and Au/CeO2 and their activity in oxidative steam reforming of methanol

Ceria (CeO2) supports, synthesized by hydrothermal treatment with different synthesis time (CeO2-X h, where X is the synthesis time in h) in the presence of the surfactant cetyltrimethyl ammonium bromide, were used as supports for gold (Au) catalysts. The synthesis time significantly affects the morphological structure and crystallite size of CeO2, where CeO2-2 h has the smallest crystallite size with coexisting nanorods and nanoparticles. Transmission electron microscopy analysis confirms the morphology of CeO2 with distinctive (110), (100) and (111) planes, in agreement with interplanar spacings of 0.19, 0.27 and 0.31, respectively. However, the morphology of CeO2-8 h and CeO2-48 h is mainly a truncated octahedral with crystal planes (111) and (100) accompanied by an interplanar spacing of 0.31 and 0.27 nm, respectively. The CeO2-X h supports and those with a 3 wt% Au loading (Au/CeO2-X h) were investigated in the oxidative steam reforming of methanol at temperatures between 200 and 400 °C. The Au/CeO2-2 h gave the highest methanol conversion level and hydrogen yield at a low temperature of 250 °C. This superior catalytic performance results from the good interaction between the metal and support and the well-distributed Au species on the CeO2 support.

Anodic aluminum oxide supported Cu-Zn catalyst for oxidative steam reforming of methanol

Oxidative steam reforming of methanol (OSRM) is autothermal and therefore well suited for hydrogen production. The exothermic part of OSRM generates heat at the reactor inlet to be used as the reaction heat for the endothermic methanol steam reforming in the rest of the reactor. With conventional particle catalysts, a hot spot is formed at the reactor inlet because of the poor thermal conductivity in the catalyst bed. The catalyst at the hot spot is deactivated by thermal sintering. Side reactions such as the reverse water gas shift reaction and methanol decomposition reaction become active at the hot spot. We developed a high-thermal-conductivity Al plate catalyst to suppress the formation of the hot spot in the catalyst bed during OSRM. In particular, a strongly bonded layer of anodic aluminum oxide as a catalyst support was grown on the Al plate surface via anodic oxidation in oxalic acid solution, and the internal surface area of the support was increased by pore widening and hot water treatments. To obtain a catalyst with high activity, multiple impregnations (>three times) and an anodization time of 24 h was needed. The catalyst was deactivated when operated at an elevated temperature of 623 K, but the activity was completely restored by a simple oxidation. Notably, OSRM was proven to be a combination of methanol combustion and methanol steam reforming reactions, and the kinetics of these two reactions were studied in detail.

Hydrogen production by oxidative steam reforming of methanol over anodic aluminum oxide-supported Cu-Zn catalyst

Oxidative steam reforming of methanol (OSRM), which is a convenient reaction for producing hydrogen, suffers from the hot spot formation problem when conventional particle catalysts are used. Recently, an anodic aluminum oxide (AAO)-supported Cu-Zn catalyst was proposed as an OSRM catalyst for its high thermal conductivity through the aluminum metal body. In this study, OSRM was conducted in a prototype reactor packed with the AAO plate catalyst strips. It was verified that the high thermal conductivity of the catalyst effectively suppresses the hot spot formation and makes the temperature profile smooth along the reactor. The start-up time of the reactor depended on the preheating temperature and was very short (less than 2 min) for preheating over 503 K. The methanol conversion and reactor temperature increased with increasing O2/CH3OH mole ratio, indicating that the mole ratio can be used as a control variable to operate the reactor at desired conditions. Further, a reactor model was developed and verified, and the simulation showed that for a given total reactor volume, an optimal reactor configuration could be achieved by shortening the reactor length while widening the cross-sectional area.

Hydrogen production from the oxidative steam reforming of methanol over Au[sbnd]Cu nanoparticles supported on Ce1-xZrxO2 in a fixed-bed reactor

Oxidative steam reforming of methanol over monometallic gold (Au) and bimetallic Au-copper (Cu) supported on ceria-zirconia (CeO2ZrO2) was examined over the temperature range of 200–400 °C in a fixed-bed reactor. The composition of CeO2ZrO2 supports was also studied for their catalytic activity. The Au/Ce0.75Zr0.25O2 catalyst exhibited the highest methanol (CH3OH) conversion level (96.7%) and hydrogen (H2) yield (59.7%) due to the formation of a homogeneous Ce1-xZrxO2 solid solution. When Cu was introduced in the Au catalysts, all of the bimetallic catalysts presented a better stability for CH3OH conversion as well as H2 yield in comparison to the monometallic catalysts, which was due to the partial electron transfer from Cu to Au metals. The performance of the AuCu/Ce0.75Zr0.25O2 catalysts, which was evaluated under identical conditions, was ranked in the order: 3Au1Cu > 1Au3Cu > 1Au1Cu.

Monometallic Ru, Au, and Pt Catalysts Deposited on Carbon Nanotubes for Oxidative Steam Reforming of Methanol

Monometallic Ru, Au, and Pt Catalysts Deposited on Carbon Nanotubes for Oxidative Steam Reforming of Methanol